I got a ich issue.... I know that there is 90 gallons in my system. How do I drop from 1.024 to 1.017 as safe as possible? I use a hydrometer, backed up by my trusty refractometer! 1. Do I just add fresh water into system and measure? 2. What is the safest rate to reduce salinity? I have a tang fetish and the fish most affected by this is my powder brown. He and the others are fed small portions 6 times a day. 2 nori clips and 4 auto feeds, approx 2-3 small pellets each.